Temat: metamorphism - Katalog OPAC zbiorów

Skocz do pozycji: 1.

Tytuł:: Shock structures in the Morasko meteorite - preliminary SEM data
Autorzy:: Brachaniec, T.
Powiązania:: https://bibliotekanauki.pl/articles/100872.pdf
Data publikacji:: 2014
Wydawca:: Uniwersytet Śląski. Wydział Nauk o Ziemi
Tematy:: shock
metamorphism
Morasko meteorite
dane SEM
metamorfizm
meteoryt Morasko
Opis:: This paper is a preliminary review of main shock deformations in the Morasko meteorite. Three main types of metamorphism structures occur in the investigated material: (i) brittle, (ii) plastic and (iii) thermal. Their interpretation may indicate, that Morasko meteorite reveals several stages of shock, eg.: extraterrestrial collisions and fall on the Earth.
Źródło:: Contemporary Trends in Geoscience; 2014, 3, 1; 1-4
2299-8179
Pojawia się w:: Contemporary Trends in Geoscience
Dostawca treści:: Biblioteka Nauki

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Skocz do pozycji: 2.

Tytuł:: Alteration of mélange-hosted chromitites from Korydallos, Pindos ophiolite complex, Greece: evidence for modification by a residual high-T post-magmatic fluid
Autorzy:: Kapsiotis, A. N.
Powiązania:: https://bibliotekanauki.pl/articles/138612.pdf
Data publikacji:: 2014
Wydawca:: Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:: Ferrian chromite
Cr-spinel
metamorphism
Ophiolites
Pindos
spinel Cr
metamorfizm
ofiolity
Opis:: The peridotites from the area of Korydallos, in the Pindos ophiolitic massif, crop out as deformed slices of a rather dismembered sub-oceanic, lithospheric mantle section and are tectonically enclosed within the Avdella mélange. The most sizeable block is a chromitite-bearing serpentinite showing a mesh texture. Accessory, subhedral to euhedral Cr-spinels in the serpentinite display Cr# [Cr/(Cr + Al)] values that range from 0.36 to 0.42 and Mg# [Mg/(Mg + Fe²⁺)] values that vary between 0.57 and 0.62, whereas the TiO₂ content may be up to 0.47 wt.%. The serpentinite fragment is characterized by low abundances of magmaphile elements (Al₂O₃: 0.66 wt.%, CaO: 0.12 wt.%, Na₂O: 0.08 wt.%, TiO₂: 0.007 wt.%, Sc: 4 ppm) and enrichment in compatible elements (Cr: 2780 ppm and Ni: 2110 ppm). Overall data are in accordance with derivation of the serpentinite exotic block from a dunite that was formed in the mantle region underneath a back-arc basin before tectonic incorporation in the Korydallos mélange. Two compositionally different chromitite pods are recognized in the studied serpentinite fragment, a Cr-rich chromitite and a high-Al chromitite, which have been ascribed to crystallization from a single, progressively differentiating MORB/IAT melt. Although both pods are fully serpentinized only the Al-rich one shows signs of limited Cr-spinel replacement by an opaque spinel phase and clinochlore across grain boundaries and fractures. Modification of the ore-making Cr-spinel is uneven among the Al-rich chromitite specimens. Textural features such as olivine replacement by clinochlore and clinochlore disruption by serpentine indicate that Cr-spinel alteration is not apparently related to serpentinization. From the unaltered Cr-spinel cores to their reworked boundaries the Al₂O₃ and MgO abundances decrease, being mainly compensated by FeO^t and Cr₂O₃ increases. Such compositional variations are suggestive of restricted ferrian chromite (and minor magnetite) substitution for Cr-spinel during a short-lived but relatively intense, low amphibolite facies metamorphic episode (temperature: 400–700 °C). The presence of tremolite and clinochlore in the interstitial groundmass of the high-Al chromitite and their absence from the Cr-rich chromitite matrix imply that after chromitite formation a small volume of a high temperature, post-magmatic fluid reacted with Cr-spinel, triggering its alteration.
Źródło:: Acta Geologica Polonica; 2014, 64, 4; 473-494
0001-5709
Pojawia się w:: Acta Geologica Polonica
Dostawca treści:: Biblioteka Nauki

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Tytuł:: Wstępna charakterystyka strukturalno-petrograficzna fyllitów z Podmąchocic w regionie łysogórskim Gór Świętokrzyskich
Preliminary structural-petrography characteristic of phyllite from Podmąchocice in the Łysogóry Unit of the Holy Cross Mts.
Autorzy:: Salwa, S.
Powiązania:: https://bibliotekanauki.pl/articles/2074459.pdf
Data publikacji:: 2006
Wydawca:: Państwowy Instytut Geologiczny – Państwowy Instytut Badawczy
Tematy:: tektonika
metamorfizm
fyllity
Góry Świętokrzyskie
tectonics
metamorphism
phyllite
Cambrian
Holy Cross Mountains
Opis:: Four tectonic deformation events are recorded in the Middle Cambrian rocks from Kamecznica Podmąchocicka. The D1 event took place in Cambrian and originated from tremor. Its structural record includes synsedimentary folds and seismites. The D2–D3, and most probably also D4, events resulted from progressive deformation produced by tectonic compression initially from NE and then NNE direction. Folding was accompanied by green facies metamorphism, which resulted in development of phyllites. Composition and characteristic deformations of minerals suggest that they were produced in temperature ranging from 300ş to 400şC and differential pressure above 1.7 kbar (170 MPa). The combined deformation and metamorphism resulted in three generations of foliation — S1 to S3 defined by crenulated cleavage planes. New blasts of quartz, small scale muscovite (sericite), chlorites and sporadically biotite grew within these cleavage planes. Deformations and metamorphism took place after the Middle Cambrian, but before the Late Silurian. It is indicated by presence of the quartzitic sandstone pebbles in the Miedziana Góra Conglomerates.
Źródło:: Przegląd Geologiczny; 2006, 54, 6; 513-520
0033-2151
Pojawia się w:: Przegląd Geologiczny
Dostawca treści:: Biblioteka Nauki

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